Rotary stirling cycle refrigerating system



Nov. 3, 1970 D. A. KELLY 3,537,269

ROTARY STIRLING CYCLE REFRIGERATING SYSTEM 3 Sheets-Sheet 1 F'IGI Filed Jan. 6, 1969 I 3/ 64,44 30 2a 29 l 9 27;; 32

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Now-3,1970 I Filed Jan. 6. 1969 ='N. v. 3,19 0 D. A. KELLY 3,531 269 ROTARY STIRLING CYCLE REFRIGERATING YSTEM Filed Jan. 6, 1969 3'Sheets-Shet 5 COOLING HEATING mvsuron United States Patent 3,537,269 ROTARY STIRLING CYCLE REFRIGERATING SYSTEM Donald A. Kelly, 58-06 69th Place,

Maspeth, N.Y. 11378 Filed Jan. 6, 1969, Ser. No. 789,303 Int. Cl. F25b 9/00 US. Cl. 62-6 7 Claims ABSTRACT OF THE DISCLOSURE The rotary Stirling cycle refrigerating system consists of a compact housing containing dual rotor bores in a closed-loop arrangement. A displacer rotor and wide vane revolve eccentrically in one bore and a vaned rotor revolves eccentrically in the adjacent bore at the same speed.

The system provides a compact heat exchange means in which the cooling medium is air, with operating torque provided by an electric motor, or other suitable power.

This invention relates to a compact rotary Stirling cycle refrigerating unit and heat exchange system suitable for applications where compact efficient closed-cycle cooling is required.

The refrigerating system is based on an inverted Stirling cycle where motor torque is converted into heating and cooling effects at adjacent sections of the unit. The ideal Stirling cycle is comprised of four phases within a closed loop, i.e., isothermal compression, the constant volume gas transfer from the displacer volume to the expander space to the displacer space to complete the cycle.

The configuration for this refrigerator unit is based on prior Rotary Stirling engine Pat. No. 3,370,418 and a modified version described in patent application Ser. No. 723,721 filed Apr. 24, 1968 and Ser. No. 741,766 filed July 1, 1968.

Various types of Stirling cycle machines are known including the dual coaxial piston type and the side-by-side piston classic type. The rotary configuration offers a simple arrangement since no phasing and connecting rodsare required, along with simplified regenerator design. Rotary Stirling machines may be arranged in two ways, which are axial flow type or the radial flow arrangement. For the refrigeration unit the radial flow arrangement is preferred since the gas flow is more direct and in a generally circular loop rather than transferred at right angles to the rotor axis.

The displacement of the gas from the hot to the cold side of the displacer stage is accomplished by a wide displacer vane which is free to move radially as the displacer rotor revolves. The displacer vane may be a free fit Within the displacer bore in a similar manner to that of the reciprocating displacer piston within its displacer cylinder. The displacer vane may also be sealed within its bore so that thermal spill-over is minimized. The displacer vane arrangement provides two equal gas volumes within the displacer bore which produce the heated and cooled sections. The pump rotor is eccentrically located in the second bore and contains two interlocking sealed vanes which provide the necessary transfer pressure for the, gas circuit. The two large bores are connected with transfer bores which form the gas circuit necessary to complete the cycle.

An alternate displacer element consists of a base halfrotor which supports a sliding displacer half rotor. The advantage of this arrangement is that the basic gas volumes and cycle sequences are more closely followed than in the displacer vane type. The circular regenerator bores in the sliding displacer half are more effective than in ice the displacer vane type since they are nearly a full half circumference within the displacer half-rotor.

In operation, the electric motor or other power source drives the pump rotor shaft and the displacer rotor through suitable gearing. Since the cycle is inverted the outside section block becomes cold and the inner or middle section block becomes hot. The outer cold section block must be completely insulated from the hot section block and provided withfins or other thermal transfer means for the specific cooling application. The middle hot section block must also be provided with suitable insulation and thermal transfer means so that efficient functioning is maintained.

The unit will function in either direction of rotation but the displacer vane regenerator inlet posts must face in the direction of rotation for correct operation.

The adoption of modular construction minimizes manufacturing costs and allows convenient separation and insulation of each section block. For convenience in manufacturing the transfer bores would be machined in the single block before the two separation cuts are made. The starting points of the bores would be plugged from the outside to maintain pressure tightness in the gas flow loop. This starting bore method allows pressure gages and inlet valves to be conveniently placed at these points, as required.

The displacer vane would be provided with zig-zag regenerator bores for effective thermal storage between the cycle phases. Inlet posts would be located at'one extremity of the vane on one face, and the outlet posts on the opposite end and face, so that effective thermal transfer from one thermal half to the same half is maintained.

The regenerator bores are fitted with regenerative filament to provide heat storage while minimizing gas flow resistance. In operation the filament would serve to store heat as the vane sweeps through the cold section and release it as the vane enters the hot section.

It must be noted that the total length of the zig-zag regenerator bores within the displacer vane must be equal to half the post are circumference so that uniform and equal thermal storage and transfer will be maintained.

The refrigerator unit as a closed cycle machine must be provided with a high temperature dry film lubricant and low friction seals so that no internal lubrication arrangement is required.

The unit may be provided with a liquid cooling system which would provide a further reduction in the cold section temperature. The circulating coolant would have the effect of reducing the hot section temperature so that the final cold section temperature is lower. The unit may also be provided with cooling fins for air cooling with the choice of no extra cooling, air cooling or liquid cooling or a combination of these, depending on the specific application of the refrigeration system.

It is an object of the invention to provide a simple and compact rotary Stirling cycle refrigeration system.

It is a further object of the invention to produce a rotary Stirling cycle refrigeration system which has few operating parts and is relatively inexpensive to manufacture.

It is an object of the inventioin to provide a refrigeration unit which operates on dry film lubrication with no additional oil lubrication.

It is an object of the invention to provide cryogenic temperatures for many applications by utilizing an auxiliary liquid cooling source.

It should be understood that variations may be made in the detail design without departing from the spirit and scope of the invention.

Referring to the drawings:

FIG. 1 is a top section view through the refrigerating unit.

' 3 FIG. 2 is a front section FIG. 3 is a front view of the displacer vane.

FIG. 4 is a side view of the displacer vane.

FIG. is a front section through an alternate refrigerating unit arrangement.

FIG. 6 is a pictorial view of the various rotating functional elements.

FIG. 7 is a P-V diagram of the inverted cycle.

REFERRING TO THE DRAWING IN DETAIL The unit block 1 is divided into three sections which are nearly equal in volume. Section 1a is the cold section, 1b is the hot section and 1c is the pump rotor section. The sections are insulated from each other by two gaskets 41 and 42 and secured together with the bolts 43. The front plate 2 and the rear plate 3 are secured to the unit block 1 by the screws 45.

The displacer rotor 4 closely fits and revolves in the displacer bore 5 in section 1a and is supported by the shaft 6 and the stub shaft 6. The two rotor bearings 7 and 29 support the displaced rotor and the shafts 6 and 6' within the unit block 1 and plates 2 and 3. The retaining flanges 8 contain the shaft seals 9 which pressure seal the shafts in the unit block 1. p Y The retaining flanges 8 are secured to the rear plate 3 with the screws 26, with a special sealant used to make a pressure tight seal between the retaining flanges 8 and the rear plate 3.

through the refrigerating unit. 7 7

about twenty in number to assure adaquate cooling for cryogenic operation. The entrance portion of the coolant holes 24 will be threaded to receive the connecting tubes 25 which are connected to a external coolant circulating system.

Three identical spur gears 27 are secured to the shafts 6, 18 and the idler shaft 28. This gearing arrangement allows the two stages to rotate at the same speed and in the same direction so that the inverted cycle may function properly.

The idler shaft 28 is supported by the two ball bearings 29 and flange 30. The flange 30 is secured to the rear plate 3 by the screws 26. The gears are locked on their respective shafts by the pins 31. A snap-on cover 32 en- The displacer rotor 4 has a diametrical slot 21 through 'in half except for the tie piece 22 at one end. The shaft 6 has a base flange 6a which is secured to the rotor 4 end by the screws 44. The stub shaft 6 also has a base flange 6b which is secured to'the opposite end of the rotor 4 by the screws 44.

The displacer vane 10 is provided with internal regenerator bores 11, which are zig-zagged to provide a full flow path. The displacer vane 10 is made up of laminated sections so that the regenerator bore 11 may be molded or formed in the necessary pattern without the necessity of plugging the bores where they break through the displacer vane walls. A side notch 11a provides clearance for the tie piece 47 of the rotor 4.

The ends and sides of the displacer vane 10 are provided with slots 11b into which the rectangular seals 12 are fitted.

The pump rotor bore 13 is located in the, unit block, section 10 and is connected to the displacer bore 5 by the multiple transfer bores '14 and 15. The entrance bores 14a and 15a are sealed with the threaded plugs 16. The thermal transfer bores 14 and 15 are offset from each other, so that the bores do not break through and short the gas circuit.

The pump rotor 17 closely fits and revolves in the pump bore 13 and is supported by the output shaft 18. The two rotor bearings 7 support the power rotor and the output shaft 18 within the engine block 1 and plates 2 and 3.

The two interacting pump vanes 19 and 20 are closely fitted into corresponding slots 19 and 20' within the pump rotor 17, and may freely move radially within these slots. The pump rotor17 has a blind bore 17a which provides clearance for the pump vanes 19 and 20.

The pump vanes 19 and 20 are provided with slots 21 at the ends and along the sides into which the rectangular seals 22 and 23 are closely fitted. The sealing arrangement for each vane consists of two long rectangular seals 22 at the vane ends and four side rectangular seals 23 at the vane sides. The ends of the adjacent seals are half-lapped so that they interlock to form a continuous sealing surface.

The unit block section 1b contains the multiple liquid coolant holes 24, axially arranged around the interior periphery of the displacer bore 5. The coolant holes 24 must cover nearly 180 degrees of the bore and should be closes the gear assembly to provide protection for the gearing.

In the alternate arrangement the displacer element consists of a base rotor half 4A secured to the shaft 6. The sliding displacer member 4B is generally semi-circular in shape, having a curvature which allows it to revolve and slide within the displacer bore 5. The sliding displacer member 4B is fitted with two angle brackets 33 which support the guide rod 34 in the middle of the displacer member 4B. The base half rotor 4A has a corresponding guide hole 35, which aligns the guide rod 34 and the sliding displacer member 4B as both displacer elements revolve within the displacer bore 5. The base half-rotor 4A is provided with a clearance flat 36 which allows the angle bracket 33 to clear the base half rotor 4A during the extreme excursions of the brackets 33.

The guide rod 34, guide hole 35 and contacting rotor flats are coated with dry film lubricant so that smooth lowfriction reciprocation is assured in operation.

Ball bearings 37 and pins 38 are uniformly located and recessed into slots 39 within the periphery of the sliding displacer member 4B, so that the member rolls freely within the displacer bore 5, at a constant close clearance.

Multiple circular regenerator bores 40 are uniformly located within the sliding displacer member 4B, with fine regenerative filament 46 uniformly disposed within the regenerator bores 40. The regenerator bores 40 are at a maximum practical radius to be most effective in operamounted flush into the recesses 4c at both ends of the base half rotor 4A.

All other elements of this alternate arrangement would be the same as in the first or sliding'vane type of refrigeration unit.

A possible variation in the pump rotor design is that the pump vanes may be smaller, independent and greater in number. The independent vanes have the advantageof not having to compensate for the difierence in length between the bore diameter and the required vane length due to the pump rotor eccentricity.

What is claimed is:

1. An inverted Stirling cycle regfrigerating unit comprising a rectangular block divided into'three nearly equal sections, two parallel large bores disposed within the said rectangular block, multiple small bores disposed at right angles to said large bores which freely communicate with the said two large parallel bores to form a continuous gas circuit, a displacer rotor eccentrically disposed in one of the said two large parallel bores, a wide diametrical slot uniformly cut into the said displacer rotor, a wide dis placer vane closely sliding within the said wide diametrical slot, multiple non-linear regenerator bores uniformly disposed within the said wide displacer vane; fine regenerative filament uniformly disposed within the said multiple non-linear regenerator bores, two flanged short shafts disposed at each end of the said displacer rotor, a pump rotor eccentrically disposed in the second of the said two large parallel bores, two diametrical slots at right angles to each other and a blind bore disposed within the said pump rotor, two slotted intermeshing pump vanes slidably associated with the said two diametrical slots of the pump rotor, an output shaft secured within the said blind bore of the pump rotor, two end plates secured to the two sides of the said rectangular block, bearing bores with bearings disposed in line with the eccentric axes of the said displacer rotor and pump rotor within the said two end plates, sealing means disposed within one of the said two end plates, sealing means disposed within one of the said two end plates where the shafts protrude from the said rectangular block.

2. An inverted Stirling cycle refrigerating unit according to claim 1, in which the said multiple non-linear regenerator bores uniformly disposed within the said wide displacer vane are equal in length to one-half the circumference of the revolving said wide displacer vane length, multiple posts corresponding to and intersecting the said regenerator bores uniformly disposed on the face at one end of the said wide displacer vane, multiple antifriction end and side seals disposed within corresponding slots at the ends and sides of the said wide displacer vane.

3. An inverted Stirling cycle refrigerating unit according to claim 1, in which the said rectangular block is provided with multiple liquid cooling bores axially disposed in the center section of the said three nearly equal sections, a liquid coolant circulating means connected to the said multiple liquid cooling bores to form a closed cooling circuit.

4. An inverted Stirling cycle refrigerating unit according to claim 1, in which the said shafts protruding from the said rectangular block are each provided with large 6 spur gears, a third spur gear supported by an idler shaft mounted to one of said two end plates and meshing with the two said large spur gears, a cover disposed over the said spur gears and secured to the said one of said two end plates, input torque means to revolve one of the said shafts.

5. An inverted Stirling cycle refrigerating unit according to claim 1, in which the said two slotted intermeshing pump vanes are fitted with rectangular end half-lapped sealing elements which are closely fitted into the said slots, the said two parallel large bores are coated with baked on dry film lubricant, the said wide displacer vane and two slotted intermeshing pump vanes are coated with dry film lubricant.

6. An inverted Stirling cycle refrigerating unit according to claim 1, in which the said three nearly equal sections are separated and insulated from each other by two thermal insulating gaskets, external bolting means provided to join the said three nearly equal sections into one rectangular block module.

7. An inverted Stirling cycle refrigerating unit according to claim 1, in which one of the said three nearly equal sections is provided with a thermal distribution means for the application of the coldness produced by the said refrigeration unit.

References Cited UNITED STATES PATENTS 3,370,418 2/1968 Kelly -24 3,413,815 12/1968 Grasuryd 626 3,426,525 2/1969 Rubin 626 3,460,344 8/1969 Johnson 62-6 WILLIAM J. WYE, Primary Examiner US. Cl. X.R. 6024 

